[dpdk-dev] [PATCH 1/2] event/sw: code refractor to reduce the fetch stall

[Van Haaren, Harry]

Hey,

> -----Original Message-----
> From: Varghese, Vipin
> Sent: Thursday, March 1, 2018 7:35 PM
> To: dev at dpdk.org; Van Haaren, Harry <harry.van.haaren at intel.com>
> Cc: Varghese, Vipin <vipin.varghese at intel.com>
> Subject: [PATCH 1/2] event/sw: code refractor to reduce the fetch stall
> 
> With rearranging the code to prefetch the contents before
> loop check increases performance from single and multistage
> atomic pipeline.
> 
> Signed-off-by: Vipin Varghese <vipin.varghese at intel.com>

There seems to be a compilation issue with this, see "const" in flow_id.
The flow_id variable is updated later, so it can't be marked const.

After the compilation fix, I see a small performance improvement here,
so you can include my Ack for V2 of this patch:

Acked-by: Harry van Haaren <harry.van.haaren at intel.com


> ---
>  drivers/event/sw/sw_evdev_scheduler.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/event/sw/sw_evdev_scheduler.c
> b/drivers/event/sw/sw_evdev_scheduler.c
> index e3a41e0..70d1970 100644
> --- a/drivers/event/sw/sw_evdev_scheduler.c
> +++ b/drivers/event/sw/sw_evdev_scheduler.c
> @@ -44,12 +44,13 @@ sw_schedule_atomic_to_cq(struct sw_evdev *sw, struct
> sw_qid * const qid,
>  	uint32_t qid_id = qid->id;
> 
>  	iq_dequeue_burst(sw, &qid->iq[iq_num], qes, count);
> -	for (i = 0; i < count; i++) {
> -		const struct rte_event *qe = &qes[i];
> -		const uint16_t flow_id = SW_HASH_FLOWID(qes[i].flow_id);
> -		struct sw_fid_t *fid = &qid->fids[flow_id];
> -		int cq = fid->cq;
> 
> +	const struct rte_event *qe = &qes[0];
> +	const uint16_t flow_id = SW_HASH_FLOWID(qes[0].flow_id);

     ^^^^^^ remove the const here.